To activate passenger protection means as a function of an acceleration-based algorithm and a structure-borne noise signal is known from M. Feser, C. Wieland, C. Schmidt, and T. Brandmeier: Crash Impact Sound Sensing (CISS)—Higher Crash Discrimination Performance at Lower Cost, Airbag 2004. This should make it possible to better detect a head-on crash and make the triggering decision more robust for critical situations. In addition, the introduction of the structure-borne noise sensor system should make the overall system more cost-effective.